The present invention relates to an apparatus and method for transferring a particulate material through a pipeline while keeping it from contact with the inner wall surface of the pipe. More particularly, the present invention relates to an apparatus and method for transferring pulverized semiconductor particles through a pipeline in a non-contact state to produce semiconductor devices.
There have been known apparatuses for transferring a particulate material through a pipeline while keeping it from contact with the inner wall surface of the pipe. The conventional transfer apparatuses employ a method wherein a powdery material is electrically charged by a multiplicity of electrodes disposed on the inner wall of the pipe, thereby allowing the powdery material to be transferred in the state of being out of contact with the wall surface of the pipeline. However, these conventional apparatuses are used to transfer a fine powdery material having a particle diameter in the range of from several micrometers to several tens of micrometers. There has been no apparatus designed to transfer a particulate material having a particle diameter of 1 millimeter or so through a pipeline while keeping it from contact with the inner wall of the pipe.
The transfer method wherein particles are electrically charged is likely to cause dielectric breakdown or other failure in the case of transferring electronic material particles, particularly finely pulverized semiconductor particles. Therefore, the method wherein particles are electrically charged by an electric field could not be adopted as a non-contact transfer method for semiconductor particles.
There has been another known non-contact transfer method that utilizes magnetic attraction and repulsion forces. In this case, however, it is essential that the object to be transferred should be a magnetic material or a substance having magnetism, or a transfer carrier made of a magnetic material should be used. Thus, the non-contact transfer method cannot be used for the purpose of transferring particles of a non-magnetic material individually.
A method of transferring an object in a non-contact state by a gas flow is carried out in a process of producing paper or other belt-shaped members. However, a gas flow is not used for non-contact transfer of particles. There has been proposed no method of efficiently transferring particles in a non-contact state.
An object of the present invention is to provide an apparatus for transferring a particulate material through a pipeline while keeping it from contact with the inner wall of the pipe. More particularly, an object of the present invention is to provide a device whereby a semiconductor material previously formed into spherical particles is transferred in the state of being out of contact with the inner wall of the pipe.
More particularly, an object of the present invention is to provide a transfer apparatus and method suitable for the production of a spherical semiconductor integrated circuit in which a semiconductor circuit is formed on the surface of a spherical semiconductor particle, which is proposed, for example, in U.S. patent application Ser. Nos. 60/0320340, 08/858004, and PCT/US97-14922 by the assignees of the present invention.
Existing integrated circuits are fabricated by forming circuits on a disk-shaped silicon wafer, and there is a tendency to use silicon wafers of larger sizes, i.e. to change over from wafers of 8 inches in diameter to wafers having a diameter of 12 inches, in order to produce a large number of semiconductor devices in a short period of time. However, as the diameter of silicon wafers increases, the size of production systems increases, resulting in a need for large-sized production facilities, e.g. clean rooms for accommodating production equipment.
In the spherical semiconductor integrated circuit proposed by the assignees of the present invention, a semiconductor circuit is formed on the surface of a spherical silicon particle without using a silicon wafer. The spherical semiconductor integrated circuit is a novel device that makes effective use of the surface area of a sphere, and it is an epoch-making invention that needs no large-scale clean room because no large-sized production system is needed. Under these circumstances, it is demanded to develop a novel method for producing the spherical semiconductor integrated circuit.